Pressure shoe structure for kinetographs



March 14, 1950 L'. w. .1l-:DEKA 2,500,358

massimak snol: STRUCTURE FOR KINETQGRAPHS Filed July 14, 1949 2Sheets-Sheet 1 1f. i v e.

L1. o yo W li-DEKA,

I N VEN TOR.

TTOQNEYS.

March 14, 195o L. w. JEDEKA 2,500,358

PRESSURE SHOE STRUCTURE FOR KINETOGRAPHS Filed July' 14, 1949 2Sheets-Sheet 2 Y; 50 l au .oyo W' Z-:DE/A,

IN V EN TOR.

Patented Mar. 14, 1950 PRESSURE SHOE STRUCTURE FOR KINETOGRAPHS Lloyd W.Jedelia, Montrose, Calif., assignor to Mitchell Camera Corporation,Glendale, Calif., a corporation of Delaware Application July 14, 1949,Serial No. 104,685

11 Claims.

This invention is concerned generally with improvements in the lmtensioning means (pressure shoes) of the type ordinarily associated withthe lm gate of a motion picture machine.

Among the primary objects of the invention are the provision of improvedmeans for controllably varying the pressure applied to the filmuniformly over the entire length of the film chute, and the provision,in certain embodiments of the invention, of independently operable meansfor varying the film tension at any one portion of the film chutewithout appreciably affecting the tension at other portions. Moreover,the invention permits both those types of adjustment to be madeconveniently and While the machine is in operation.

The invention further provides tension controlling mechanism which isconveniently accessible and can be readily disassembled for cleaning orfor the replacement of parts. In particular, the individual springswhich determine the lm tension at various portions of the film chute areindependently removable without the use of any special tools, and hencecan be quickly replaced if desired, either individually or as a group,by springs having different characteristics. That leads to a iiexibilityof operation which facilitates the optimum overall performance of themachine under a wide variety of operating conditions and with filmhaving varying characteristics.

An understanding of the invention, and of its other objects andadvantages, will be had from the following illustrative description ofcertain typical embodiments. Details of that description, and of theappended drawings Iwhich form a part of it, are not intended as alimitation upon the scope of the invention. For example, for clarity ofdescription the lm tensioning mechanism is here considered to beincorporated in a motion picture projection machine, but the inventioncan be used also in other kinetographio mechanisms, such as cameras,printers, etc. While the mechanism of the invention is preferablyincorporated in the movable element of a film conning means, it will beunderstood that such mechanism can alternatively ibe mounted in thefixed portion, or can be associated with lm guiding means which do notinclude any openable gate structure. Also, the mechanism is described ashaving the usual operating position with respect to gravity, but suoliterms as vertical and horizontal are used only for convenience ofdescription and not by way of limitation. Similarly, other modificationsand rearrangements of the structures here specically lil described areintended to be included within the scope of the invention.

In the drawings:

Fig. 1 is an elevation, partly broken away, of a preferred embodiment ofthe invention, looking along the optical axis toward the light source ofa motion picture projection machine;

Fig. 2 is a vertical section on line 2-2 of Fig. 1;

Fig. 3 is a horizontal section on line 3 3 of Fig. 1 and including inpartially schematic form the iilm trap of the motion picture machine;

Fig. 4 is a schematic perspective of the primary moving parts of themechanism of the preferred embodiment of the invention;

Fig. 5 is a horizontal section on line 5-5 of Fig. 1;

Fig. 6 is a horizontal section showing a modiiication and taken asindicated by the line 6 6 of Fig. 1;

Fig. 7 is a fragmentary section taken in the same aspect as Fig. 1 andshowing a modification; and

Fig. 8 is a fragmentary section similar to Fig. 6 but illustrating afurther modication.

In the preferred modication illustratively shown in Figs. 1 5, thenumeral 20 indicates generally a film gate. Film gate 20 is movable(downward as seen in Fig. 3, and to the left as seen in Fig. 2) awayfrom the Xed portion or film trap 22, to provide access to the filmchute 24, as for threading. As illustrated, the gate is rigidly securedto a gate carrier 2|, which is movable, by means not shown, to open thegate. Releasable means, also not shown, is provided for holding thecarrier and gate in the normal operating position of Fig. 3. Film chute24 is defined primarily by a vertical channel in the face of trap 22,deiining raceways 25, which receive and guide the lm 2G past theopposing face of gate 20, as shown in Fig. 3.

An aperture plate 3l) is removably mounted in film trap 22. The plateenters a horizontal channel 32 spaced back of vertical film chutechannel 24. An embossed portion of the aperture plate projects forwardinto an aperture between the two channels. The picture aperture 3S islocated in that embossed portion, and is spaced from, but immediatelyadjacent the nlm 26, where it can most effectively define the portion ofthe lm to be projected. Aperture plate 30 is secured in a definedposition in channel 32. The plate ts the channel accurately in itsvertical dimension, and is pressed against the iront channel wallnearest the nlm by three spring pressed balls which are mounted in boresin the rearward Wall of the channel, as indicated at 3B. ri'wo balls, ofwhich only one is seen in Fig. 3 at engage the flat rearward face of theaperture plate near its outer end, one above and one below itshorizontal axis. The third ball il is located on that horizontal axisnear 'the inward end of the plate, and engages the slanting face of alip 42, thereby urging the plate not only toward the forward face of thechannel, but also further into the channel, so that handle fil-iof theplate seats firmly against the outer wall of nlm trap 22, deiinin(T thelongitudinal. position of the plate in the channel.

The lm gate itself comprises a frame or housing 50 which includes faceplate 52, upper and lower end walls 53 and Eil, outer Side wall T55, andinner side wall A cover plate 58 is removably secured to the housing bytwo screws producing a closed chamber in which the film tensionmechanism is principally housed. Gate 2t is rigidly but removablymounted on gate carrier El by means of two studs t5 on the carrier,ywhich enter locating holes 5I in thickened portions El' o inner gatewall 556 (Fig. 5). Th ends of studs E are threaded and are received bythe internally threaded inner ends of the elongated clamp knobs 62.Those clamp knobs t loosely7 in bores S and 68 in outer gate wall 555and in guide bosses til, respectively, in which they are removablyretained by snap rings lll. The outer ends of clamp knobs 62 carryknurled handles 63 which are conveniently accessible to the operator ofthe machine just outside outer gate side Wall 55. When clamp knobs G2are tightened on threaded studs te, their inner end faces bear directlyupon bosses of inner gate wall clamping the latter firmly and directlyto gate carrier 2|, without imposing any strain upon the gate trame as awhole.

Means for intermittently drawing film F through lm chute 2t pastaperture 34 are indi cated partly schematically by intermittent sprocketA'l5 in 2, that sprocket being inter mittently driven by any suitablemeans, such asV a Geneva movement, not shown. The nlm is resilientlyheld in engagement with sprocket by a sprocket pad l5, which is not initself a part of the present invention. Sprocset pad 'l floats underadjustable spring pressure on a stud ll mounted on a tongue T8 thatdepends from the lower end of gate frame 50. The rotational motion ofthe sprocket pad about the axis of stud "il is accurately limited by theplay of an arm "ld, fixed on the pad frame, in a groove lil in the gateframe, thereby insuring that the pad will engage sprocket l5 correctlywhen the gate is. closed.

In each cycle oi' lm movement, the film is ac-v celerated downward byintermittent sprocket 'l5 and is then brought to rest-in film chute byfilm tensioning means which press the film against raceways 25 andthereby subject it to friction. To obtain smooth and satisfactory nhaction, that friction must be suciently great and correctly distributedalong the length of the Iilm chute to prevent the lm from piling up assprocket 'l5 comes to rest; and yet must not place an unnecessary dragon the film during its acceleration. As will be evident from thefollowing description, the present invention permits more complete andmore convenient control of the film tension, and particularly of itsdistribution along the length of the film chute, than has beenpreviously available.

Film tensioning pressure is applied to film 2G in film chute 24 by aseries of pressure shoes spaced. longitudinally along the nlm, andpressing the iilm against raceways 25. Any suitable number ot' shoes maybe provided, and these may have various individual structures andarrangements with respect to film aperture S4. In the present preferredembodiment three pressure shoes are employed, upper shoe central shoe QSand .lower shoe 83. Upper shoe 8U, for example, includes two at railsBl, parallel'to each other and to the plane of the lm, longitudinalflanges along the inner rail edges and normal to the plane of the nlm, asingle transverse connecting bar 83 extending between ilanges t2 andconnecting the rails ill to form an effectively rigid unit, upstandingrail guide pieces S4 which iorin smooth continuations of rails SI atboth their Connecting bar 33 lies inside gate housinm U, spaced fromi'ace plate 52. Rail flanges project through slots 85 in the face plateanc. support the rail faces outside the gate housing in position tocontact a film in iilm channel 2i. Gu" c pieces 811 not only insure saieand gentle agement between the lm and the rail ends by pi ovidingsmoothly curved surfaces 51 at those points, but project inwardlythrough slots in face plate 52, thereby guiding the shoe. ln particular,guide pieces Sil, by contact with the sides and ends of slots 35, limitboth the translational and the rotational movement oi the shoe in plane1 the iilm, thereby limiting rail Contact i. film to the desiredportions of the iilm adjacent its edges; but leave the shoesubstantially irce for floating movement transversely ol the hlm plane.That movement is limited outwardly by contact of bars 83 with the innersurface of face plate 52.

Lower shoe 8G, as illustrated, is substantially identical with the uppershoe, and its various parts are identiiied by the same numerals as thecorresponding parts just described lor the upper shoe. The lower shoe isset in slots i ace plate 52. The structure of central shoe is similar,but differs :from upper and lower shoes et and 86 in having twoconnecting hars 93 and 94 cio tending between the rail flanges Si?. neartheir i ends and effectively rigidly connecting the tivo flat rails 9|.Guide pieces 99 are similarly formed and perform a dual function similartc that of guide pieces 34 of the upper and lower shoes, providingsmoothly curved rail end portions and limiting shoe movement parallel tothe plane ci the lm by contact with suitable slots, as F39, in faceplate 52. Those slots are preferably formed as extensions of lightaperture B8, indicated most clearly in Fig. l. Outward motion of centralshoe 99 is limited by contact of connecting bars S93 and 94 with theinterior surface oi plate E2 between slots SS above and below lightaperture 93 (Fig. 2).

Each oi the pressure shoes is preferably formed from a single piece oisheet stock, suitably shaped and formed. Guide pieces Si, and .'liarepreierably continuations of rails Bl and lili respective for thereason already explained, and may be simply folded against the ends orrail flanges and B2.

" Alternatively, the joints between ends and guide pieces may be maderigid, as by welding. An important advantage of the present prestructure is the fact that the longitudinal 82 and 2 greatly stiifen therails, tendin vent warping during heat treatment, a'

face. .u

vantage is obtained without adding 'to the pense or complication ofmanufacture.

Outward motion ci the three pressure shoes is atomes 5 resiliently urgedby spring pressed levers |00, |02 and |03 which contact the midpoints ofconnecting bars 83 of upper shoe 80; 93 and 94 of central shoe 90; and83 of lower shoe 30, respectively. As illustrated, all four of thoselevers are pivoted for free movement on the same rod |04, which isparallel to the nlm contacting rails of the pressure shoes, and to lmchute 20. Each of those levers comprises a bell crank, having a bodyportion an arm |06 extending from that body portion generally parallelto gate face 52 and terminating in a projecting tip |01 which definesthe point of Contact with the pressure shoe connecting bar; and arelatively shorter arm ||0, extending from the body portion generallynormally to gate face 52 and carrying a formation adapted for receivingspring pressure.

Each of levers |00| 03 is independently rotatable about the axis of thecommon pivot rod |34. The body portions of the levers fit with movementfreedom in recesses ||6 formed in the vertical interior corner of gatehousing 50, which is thickened along face plate 52 to form a low shelf|20, and along outer wall 55 to form a higher shelf |22. Recesses IIS,as shown, extend throughout the cross section of both of those shelves(see, for example, Figs. 5 and 6) The axial position of the levers alongpivot rod |04 is thus fixed by contact of the axial faces of their bodyportions with the shoulders of recesses H6.

Pivot rod |04 is mounted in the frame in an economical and convenientmanner, providing', among other advantages, ready disassembly of theentire unit of rod and levers. The rod is received in a groove in theface of lower shelf |20, immediately adjacent the base of shelf |22, asshown, for example in Figs. 5 and 6. Rod |04 is located axially by gateend walls 53 and 54, and is retained in groove |25 by clamp knobs 02.After disassembly of the spring mechanism (see below) the rod isimmediately removable together with levers |00-I03 upon removal of theclamp knobs from their bores, which requires only the release of snaprings 10.

Resilient pressure is controllably applied to the arms |0 of levers 40S-|03 by individual springs, which are illustratively shown as coilsprings |26-|29, respectively, acting in a plane parallel to that offace plate 52 and hence parallel to the plane of the film 26 (Fig. 3).Each coil spring acts between its associated lever arm Ill) and a rail|30. The loading of all the springs is simultaneously adjustable bytranslational motion of rail |30 in the plane of action of the springs.Means are preferably provided for producing such translationaladjustment of rail |30 without unduly restricting rail rotation in thatplane of action. As illustrated, adjusting screw |35, car rying aknurled knob at its outer end, is screw threaded in outer gate side wall55, and engages a longitudinally central point of rail |30. A knurledlock nut |31 releasably locks screw |35 in its adjusted position. Theinner, rail engaging end of screw |35 has an axially facing shoulder |38which presses against the flat outer face of rail |30, tending tostabilize the rail against rotation about its own longitudinal axis.Screw |35 terminates beyond shoulder |38 in an axial defining pin |30,which freely enters a hole in the rail, limiting the relative motion ofrail and screw in the plane of the paper in Fig. 2, and therebymaintaining screw engagement with the rail under the combined force ofthe four springs, but leaving the rail substantially free to rotatethrough at least a small angle in the plane of the 6 spring action,which is the plane of the paper in Fig. 1.

Coil springs IZB-|29 are preferably guided by guide rods extendingaxially of the springs between rail |30 and the respective lever armsH0. Two types of such guide rods are illustratively shown in thepreferred modification of Figs. 'l-5. Guide rods |40 and |43, associatedwith springs |26 and |29 respectively, extend parallel to gate face 52across the entire width of the gate housing from holes |46 (shownillustratively as blind holes) in outer gate wall 55 to holes |41 ininner gate wall 5B. The rods are readily removable through wall 56 uponremoval of cover plate 58, being normally retained in position by tabs|48 on cover plate 58, which extend into recesses in the exterior faceof wall 56 and cover holes |41 (Fig. 1). The rods pass freely throughholes near the ends of rail |30 and between the bifurca tions I at theends of arms l0 of levers |00 and |03 respectively, thus serving notonly to guide springs |26 and |29, but also to maintain rail |30 in aplane parallel to gate face 52, while freely allowing translational railmotion parallel to the guide rods and also limited rotational railmotion in their plane about the inner end of ad justing screw |35.Spring guide rods Uil and |43 are rigidly mounted, as by riveting, onrail |30, extending from the rail axially of springs |27 and |28,respectively, and passing freely between, and only a short distancebeyond, bifurcations i i on arms H0 of levers |0| and |02, respectively.

Upon partial or complete removal of spring guide rods |40 and |43, inthe manner already described, springs |26 and |29, respectively, areindependently released and can be lifted out of the gate housing forcleaning or replacement. The remaining elements of the spring assembly,comprising rail |30, guide rods |4| and |42 and springs |31 and |38, arethen immediately removable by withdrawing guide pin |39 from its seat inrail |30. That may be accomplished by backing oif adjusting screw |35,or (if it is preferred not to disturb the adjustment of that screw) bymoving rail |30 to the right as seen in Fig. 1, compressing springs |31and |33, until the rail is clear of pin |39.

A further advantage of the structure described is the floating action ofrail |30, whereby it is free to rotate through a small angle about guidepin |39 in the plane of Fig. l. Such action tends to distribute theresilient load uniformly over springs |25 to |29, increasing theireffective resiliency under operating conditions. Thus if an abnormallythick portion of film enters film guide 24, successively engaging therespective pressure shoes, each shoe is enabled to accommodate itself tothe change in lm thickness not only by the inherent resiliency of itsassociated. spring or springs, but also by resilient movement of rail|30 which involves resilience of all the springs.

Alternatively, all four springs 11M-|29 may be guided by rods like |40and |43 in ixed relation to frame 50, or by rods like itl and |42 fixedon rail |30. In the latter instance, means other than rods |40 and |43are preferably provided to maintain rail |30 in the correct plane. Asseen, for example, in Figs. 2 and 3, that function can conveniently beperformed by the face of shelf |22 which is parallel to that plane andimmediately adjacent rail |30. The ends of lever arms i le can beprovided with other means, such as holes, instead of bifurcations I, forreceiving the guide rods, regardless of the manner of mounting thelatter. However, particularly when the guide rods are mounted rigidly onrail |30, the illustrated structures III are preferred because theentire assembly of rail, springs and guide rods can then be disassembledas a unit by simply lifting it out of the gate housing after backing offadjusting screw H35. An important advantage of that ease of disassemblyis that the springs can be replac --d quickly and conveniently. That isuseful both because of the possibility of breakage and to facilitatevarying the spring constants of one or more of the springs in order tomodify the nlm tensioning action of the mechanism. in any desired mannerbeyond the capacity of the regular adjustment provided. With springguide means such as guide rods Ido and M3 mounted in the gate frame,replacement of individual springs is even simpler than by the methodjust described for guide rods mounted on the rail. After removing coverplate E cach frame mounted guide rod can be independently removedthrough inner gate wall 5,56, releasing its associated spring withoutdisturbing the rest of the mechanism in any way.

It will be understood that spring guide means may under somecircumstances be dispensed with entirely. For example, with coil springsof suitable length and stiffness, the spring ends may simply be seatedin delining recesses in the respective pressure receiving members. Anindividual spring may then be removed directly by coinpressing it enoughto free one end from its recess. While coil springs acting undercompression are preferred, springs of other types may be used, or coilsprings can be arranged to transmit resilient force under tension fromthe translationaliy adjustable rail to the individually movable levers,those elements being rearranged accordingly in the gate housing.

Figs. 6 8 illustrate typical modications yof the structure shown inFigs. l-5, by which provision can be made for individually andseparately adjusting the pressure exerted by each pressure shoe againstthe nlm, while retaining the uni form adjustability of all pressureshoes simultaneously by a single control. As illustratively shown in 5,rail corresponding to rail ISG of the modification of the precedingfigures, is of solid rather than channel section. Spring guide rod 24E)has an enlarged threaded outer portion 239 which is screwthreaded in abore in rail 238. The outer end of rod Mii extends freely through anaperture 250 in outer side wall 55 of the gate housing and is thereforereadily accessible to the operator. A tool receiving formation 25| isshown, by which the rod can be rotated to vary its axial position withrespect to rail 230. Alternatively, a thumb nut or any other type `ofcontrol formation can be substituted for 25|. Spring 122. by whichresilient force is controllably applied to lever Illu, acts between arinI Iii of the lever and a shoulder iii! on rod that shoulder convenientlybeing -formed at the inner end of enlarged rod portion i239. Tins thetension oi spring E23 (for any given lever position) depends both uponthe position of rail 230 in the housing, controlled by master adjus tingscrew before, and also upon the threaded position of guide rod withrespect to the rail, controlled by adjustable rotation ci the rod bymeans of formation iEi. In the modiiication of Fig. spring releasable bysimply backing off screw until its threads become disengaged from railand then withdrawing rod 24S through the hole 25S in front wall :55 ofthe gate housing. Similar structures are preferably pro- D Ul vided forindividually adjusting the springs associated with levers IBI, |332 andID3. Thus the pressure of each lever against its pressure pad bar isseparately variable by adjustment of the individual screws such as i339;and the pressure of all levers is also Variable simultaneously andsubstantially uniformly by adjustment of the single screw |35.

When it is required to make the tension adjustment of the springs at oneend of rail IES different from that at the other end, it is ordinarilypreferable to prevent the rail from. swinging about thc end of screw H35in the plane of Fig, l, since such swinging or floating action tends toeliminate such tension dillerences. In the modification of Fig. 6, therail is stabilized against such swinging by guiding action of springguide rod 240. The inner end of that rod enters a bore in inner gatewall et, which is preferably thickened for the purpose as indicated inthe figure. Rod MG is freely movable axially in bore 254 to accommodateeither its own adjustment relative to rail 21?@ or the adjustment of therail and rod e. unit relative to the housing. But swinging motion of therail and rod unit about any axis but that oi bore 25d is prevented. isin the case of guide rods itil-ifi() of the previously describedmodification, the guiding function just described can be shared by allor by any number oi the spring guide rods. Those rods not required toguide rail may bc cut off a short distance inside the lever arm IIU(see, for example rod Mil in Fig. 7).

An alternative manner oi guiding rail 239 is illustrated in "c, 7. Thatguiding means is shown in connection. with a rail 33t of channel type,but is equally applicable with other types of rail and can also beemployed if des; ed in a modification which does not involve inc dualspring adjustments (Figs. l-5). As typically shown in 'g. 7, the mainadjusting sore; 'i315 is of larger diameter than corresponding screw ISBin Figs. 1-5, and has at its inner end, which bears against rail iwf anaxial bore y A pin E is www, -J mounted on rail with its airis rigidly.fn .d

' with respect to the rail, and is received by bore 33|. Rail 33t) isthus .maintained parallel to wall 54, its spacing from that wall beingadjustably variable by rotation of screw 335.

Fig. 7 shows also an alternative manner of making the spring guide rodsaxially adjus e with respect to the rail. The threaded portion of rodSill) carries a square nut which between the side of channel rail whereit is held by the force of spring 32'..

A further illustrative inodication shown in Fig. 8, in which the springguide rod is adjustably related to lever slib rather than to the rail[1351. As shown, guide rod. Mil is threaded into a sleeve 450 which ispivotally -ated to the biurcated end of lever arm fil-: by means oftrunnion pins 452. Those pins are held by spring pressure in grooves inthe lever erin bifurcations, preventing sleeve rotation about the rodncris, but permitting ready disassembly. g MESI acts It will beunderstood that many other arrangements can be employed within the scopeof the invention for independently varying the tension of the springswhich act between the adjustable rail and the respective levers whichactuate the pressure shoes. The specific embodiments described andillustrated herein are illustrative of the invention, but are notintended to limit its scope, which is defined by the following claims.

I claim:

1. In a kinetograph mechanism, nlm tensioning means comprising, a frame,means for guiding a motion picture nlm past the frame, a plurality ofpressure shoes movably mounted in the frame for yielding contact with aface of the nlm at longitudinally spaced points thereof, a plurality oflevers mounted in the frame for independent rotation about pivot axesparallel to the film, and adapted by virtue of such rotation to exertpressure upon the respective pressure shoes in a nlm contactingdirection, an elongated pressure bar mounted in the frame generallyparallel to the film and capable of movement in translation transverselyof its length, a plurality of springs acting in the plane of movement ofthe pressure bar between the respective levers and longitudinally spacedpoints of the pressure bar, said springs tending to rotate the leversabout their respective pivot axes, and manually operable means forcontrolling the said translational movement of the pressure bar to varythe tension of the springs.

2. Film tensioning means as defined in claim 1 and in which the saidlevers are mounted for independent rotation about a common pivot axis.

3. Film tensioning means as defined in claim 1 and in which the pressurebar is engaged by the said manually operable means at a single pointintermediate its length, and is rotatable about that point in its saidplane of movement in response to differential tension of the saidsprings.

4. In a kinetograph mechanism, film tensioning means comprising ahousing having a face Wall and a longitudinal side wall, means forguiding a motion picture film past the face Wall in a direction parallelto the side wall, a plurality of longitudinally spaced pressure shoesmovably mounted in the face wall for yielding contact with a face of thefilm at longitudinally spaced points thereof, a plurality oflongitudinally spaced levers mounted in the housing for independentrotation about pivot axes parallel to the nlm, and adapted by virtue ofsuch rotation in an actuating direction to positively move therespective pressure shoes in a film contacting direction, an elongatedpressure bar mounted in the housing parallel to the side wall andcapable of movement in translation transversely of its length in amovement plane generally parallel to the face wall, a plurality ofsprings acting between the respective levers and longitudinally spacedpoints of the pressure bar, said springs exerting resilient force uponthe levers tending to rotate them' about their respective axes in saidactuating direction, and exerting resilient force upon the pressure bartending to move it in translation, and manually operable control meansextending through the side wall of the housing for positively moving thepressure bar in translation in opposition to the force of the springs.

5. Film tensioning means as defined in claim 4 and including a pluralityof independently operable adjustment means for varying the tension ofthe respective springs independently of the position of the pressurebar, said adjustment 10 means extending through the side wall of thehousing.

6. Film tensioning means as defined in claim 5, and in which the saidcontrol means comprises a screw in threaded relation to the side walland engaging the pressure bar at a point intermediate its length, andthe said adjustment means comprise screws in threaded relation to thepressure bar, and having axial surfaces receiving the thrust of therespective springs, the side Wall having apertures through which thescrews are operable from outside the housing.

7. In a kinetograph mechanism, film tensioning means comprising ahousing having a face wall and a longitudinal side wall, means forguiding a motion picture nlm past the face wall in a direction parallelto the side wall, a plurality of longitudinally spaced pressure shoesmovably mounted in the face wall for yielding contact with a face of thefilm at longitudinally spaced points thereof, a plurality oflongitudinally spaced spring means mounted within the housing and actingto urge the respective pressure shoes resiliently in a film contactingdirection, manually operable control means for simultaneously varyingthe tension of the plurality of spring means, and adjustment meansoperable from outside the gate housing for separately varying thetension of each of the spring means independently of the condition ofadjustment of the said control means.

8. Film' tensioning means as defined in claim '7 and in which the saidcontrol means and the said adjustment means extend through the side wallof the gate housing.

9. In a kinetograph mechanism, nlm tensioning means comprising a housinghaving a face wall, two opposing longitudinal side walls, means forguiding a motion picture film past the face wall in a direction parallelto the side walls, a plurality of longitudinally spaced pressure shoesmovably mounted in the face wall for yielding contact with a face of thefllm at longitudinally spaced points thereof, a plurality oflongitudinally spaced spring guide rods extending transverselv withinthe housing, a coil spring surrounding each of the guide rods, alongitudinal pressure member mounted for translational movement parallelto the transverse guide rods and engaging one end of each of the coilsprings, means for transmitting pressure from the otherl end of eachspring independently to one of the pressure shoes in a direction to urgeit into film contact, control means for adjustably varying thetranslational position of the pressure member, apertures in one of theside walls coaxial with the respective spring guide rods and throughwhich the guide rods are independently axially movable for independentrelease of their associated springs, and retaining means for releasablyretaining the guide rods within the housing.

10. In a kinetograph mechanism, nlm tensioning means comprising ahousing having a face wail, a removable cover plate for the face of thehousing opposite the face wall, means for guiding a motion picture lrnpast the face wall, a plurality of pressure shoes spaced longitudinallyof the film and mounted in the face wall for yielding contact with aface of the nlm at longitudinally spaced points thereof, a plurality oflongitudinally spaced spring guide rods extending transversely withinthe housing, a coil spring surrounding each of the guide rods, alongitudinal pressure member mounted for translational movement parallelto the transverse guide rods retaining means for releasably locking theguide l rods against the said axial motion, the said retaining meansbeing mounted on the cover plate and removable therewith to release theguide rods.

1l. ln a kinetograph mechanism, iilm tensioning means comprising a gatehousing having a face wall and two opposing longitudinal side walls,means for guiding a motion picture nlm past the face wall in a directionparallel to the side walls, a gate support externally adjacent one sidewall of the gate housing, two elongated clamp knobs in threaded relationwith the gate support and having abutments adapted to clamp the said oneside wall of the gate housing to the gate support, the clamp knobsextending transversely of the gate housing through apertures in itsother side wall and being removable from the gate housing through thoseapertures, a pivot rod extending longitudinally within the gate housingbetween the clamp knobs and the face (Y wall, abutments in the gatehousing laterally ad- 12 jacent the rod and determining its position ina plane parallel to the face Wall, a plurality of longitudinally spacedpressure shoes movably mounted in the face wall for yielding contactwith a iace of the film at longitudinally spaced points thereof, aplurality of longitudinally spaced levers mounted on the said pivot rodfor independent pivotal movement thereon and adapted by such movement inan actuating direction to exert upon the respective pressure shoesforces urging them into iihn Contact, spring means engaging therespective levers and inclependently urging their respective pivotalmovement in the said actuating direction, the pivot rod and the leversmounted thereon being releasable from the gate housing upon removal ofthe said clamp knobs.

LLOYD W. JEDEKA.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,037,325 Roebuck Sept. 3, i9121270.866 Power s July 2, 1918 2,204,884 Brenkert June 18, 194D 2.211,826Kindelmann et al. Aug. 20, 1940

